When we created the Preset Phrases we wanted to make sure the Drum kit we liked was always automatically selected. So we created these phrases with a Phrase Voice which is a Program Change embedded a the beginning of the phrase data.

You can turn this Phrase Voice off by going to Pattern Mode F5 Track Voice, and selecting Off for the Track with the Preset Phrase that you want to change Drum kits on. This is on Page 218 of the manual. Then you can select a new Voice in Mix Mode, F3[Voice].

If you want to create your own Phrases that have a Program Change embedded in it, instead of selecting the Voice in Pattern Mix Mode F3 Voice, Select the Voice when in Pattern Rec on F2 Voice and this will embed a Program Change in the phrase data. This is on Page 222 of the manual.

This Track Voice feature is really more for internal development and third party software developers who want to develop libraries of phrases that will playback correctly without having to manually select a voice.